1. Field of the Invention
The present invention relates to substantially non-aqueous lubricants and lubricant compositions, and to their use, for example, to treat or lubricate containers and conveyor systems for containers. The invention also relates to containers and conveyor systems treated with a substantially non-aqueous lubricant or lubricant composition. The container is, for example, a food or beverage container.
2. Description of Related Art
Containers are receptacles in which materials are or will be held or carried. Containers are commonly used in the food or beverage industry to hold food or beverages. Often lubricants are used in conveying systems for containers, to ensure the appropriate movement of containers on the conveyor.
In the commercial distribution of many products, including most beverages, the products are packaged in containers of varying sizes. The containers can be in the form of cartons, cans, bottles, Tetra Pak packages, waxed carton packs, and other forms of containers. In most packaging operations, the containers are moved along conveying systems, usually in an upright positions, with the opening of the container facing vertically up or down. The containers are moved from station to station, where various operations, such as filling, capping, labeling, sealing, and the like, are performed.
Containers, in addition to their many possible formats and constructions, may comprise many different types of materials, such as metals, glasses, ceramics, papers, treated papers, waxed papers, composites, layered structures, and polymeric materials. Any desired polymeric materials can be used, such as polyolefins, including polyethylene, polypropylene, polystyrene, and mixtures thereof, polyesters such as polyethylene terephthalate and polyethylene naphthalate (PEN) and mixtures thereof, polyamides, polycarbonates, and the like.
Lubricating solutions are often used on conveying systems during the filling of containers, for example, with beverages. There are a number of different requirements that are desirable for such lubricants. For example, the lubricant should provide an acceptable level of lubricity for the system. It is also desirable that the lubricant have a viscosity which allows it to be applied by conventional pumping and/or application apparatus, such as by spraying, roll coating, wet bed coating, and the like, commonly used in the industry.
In the beverage industry, it is also important that the lubricant is compatible with the beverage so that it does not form solid deposits when it accidentally contacts spilled beverages on the conveyor system. This is important since the formation of deposits on the conveyor system may change the lubricity of the system and could require shut-down of the equipment to facilitate cleaning.
It is also important that the lubricant can be cleaned easily. The container and/or the conveyor system may need to be cleaned. Since water is often in the cleaning solution, ideally the lubricant has some water soluble properties.
Currently, containers, including polyethylene terephthalate (PET) bottles, and/or the conveying system are often coated with an aqueous-based lubricant to provide lubricity to the container so that it can more easily travel down a conveyor system. Many currently used aqueous-based lubricants are disadvantageous because they are incompatible with many beverage containers, such as PET and other polyalkylene terephthalate containers, and may lead to stress cracking of the PET bottles. Furthermore, aqueous based lubricants are in general often disadvantageous because of the large amounts of water used, the need to use a wet work environment, the increased microbial growth associated with such water-based system, and their high coefficient of friction. Moreover, most aqueous-based lubricants are incompatible with beverages.